Bentonite Processing Assignment Example | Topics and Well Written Essays - 2250 words

Bentonite Processing - Assignment Example Drying operation reduces the moisture content in bentonite rock to the required percentage. Different driers can be used in the moisture reduction. Drying effectively vaporizes the liquid level contain in the rocks. The vaporization is achieved through heat supply to the wet bentonite rock feedstock. The heat from the burner is supplied either through convention, radiation or conduction. The convection method is applied when direct driers are used while conduction method is applied when contact or indirect dryers are used. Most of the driers use hot air as the drying medium. This moisture removal process is an energy-intensive operation since the amount of latent heat of vaporization required is depended on the intensity of the heating (Gillson & Bances,   87).Drying curve  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   A representation curve is required so as to describe the various drying properties for different product at different specific temperature, pressure and velocit y conditions. The drying curve for bentonite rock has three different phases. These phases are useful in the energy saving process and are independent. The products are passed through these phases in shifts. After passing from one phase, the product is moved to the next phase.First phase  Ã‚  This phase is also called initial period. In this phase, there is transfer of heat from the dryer to the products and the contained moisture. Inlet condition from the dryer heats up the products and this condition further enable subsequent processes to occur. This phase can be substituted by pre-processing. Pre-processing is achieved through preheating the bentonite rock with energy from the waste material. The amount of energy from the waste material would be able to cause dislodgement of moisture contents from the bentonite surface. Second phase This phase is also called constant rate period. In this phase, free moisture attaches themselves on the surfaces. Alteration of the rate of evaporation reduces the moisture content. In this period, high drying rates are achieved through increase in the temperature of the inlet air. This phase accords the product with very little temperature increase. However, this little temperature increase is enough to cause some kinetic energy rise within the rock particles. Third phase This phase is also known as the falling rate period. Intrinsically attached moisture evaporates from the product. The product drying rate is limited by the outer surface. The outer surface provides a barrier that prevents successive evaporation rate. The evaporated moisture would be accumulated within the dryer. Moisture content The drying process employed is control by the moisture content of the bentonite rock. The dryer in this case is required to reduce the moisture content from 11% to 4%. The exact moisture content required is measured by the electrical resistance meter. However, this meter is limited to moisture content in grains, woods, food and